Process for the manufacture of aluminous cements



Patented Dec. 4, 1928.

UNITEDQSTATES PATENT OFFICE.-

- LOUIS GABRIEL PATBOUILLEAU, OF PARIS, FRANCE, ASSIGNOB TO SOCIETE ALUHINE ET DEBIVES, OF PARIS, FRANCE, A JOINT-STOCK COMPANY ORGANIZED UNDER THE LAWS OF THE REPUBLIC OF FRANCE.

PROCESS FOR THE MANUFACTURE OF ALUMINOUS OEHENIS.

No Drawing Application filed August 10, 1925, Serial No. 49,456, and in France Deceinber 19, 1924.

Experience has shown that the method con-. sisting in melting at a high temperature amixture of 'bauxites or of aluminous earths and of lime-stone or of lime, always produces a l heterogeneous substance on account of the silica present in the bauxites or aluminous earths, because the aflinity of silica SiO for lime, at the temperature considered, produces, at first, a vitreous slag consisting of a multiple silicate,wit-houthydraulie characteristics, notably more fusible than the combination of aluminum and calcium aimed at, and, consequently, does not give the desired result.

Applicant has noticed that the metallurg 16 cal process for the treatment of metallicsihcate, in particular garnierite, (double silicate of nickel and magnesium) process known under the name of sulphurizing fusion, hinders the phenomenon of silicatization men- 2 tioned above and could perfectly be applied to the production of melted aluminous cements, in a homogenousstate, capable of hardening rapidly and of high resistance.

The present invention has therefore for its object the use of the process of sulphurizing fusion in the manufacture of' aluminous cements having as a basis, a mixture of bauxite or aluminous earths, and of lime-stone or lime. The invention consists in adding to this mixture sulphur or compounds of sulphur capable'of re easing SO which constitutes an obstacle to silicatization,or dissociates this silicatization if already formed. These additions can be effected either in the mixture before introduction into the furnace, or dur-' ing this introduction, or even during the course of baking.

The present invention finally has for its object, as a new industrial product, aluminous 4'0 cements obtained by means of the above process.

In the examples cited below for the further understanding of the process, the centesim compositions are given as indications, but are not given in a limitative way, as they can vary within fairly considerable limits without influencing the result; they tend to form a product having the general formula: SiO

' replace the sulphur '2AI O 4Ca0 or: oxy-silico-aluminate of calcium.

Ea'ample 1. Thefollowing mixture, either briquetted or not, is baked:

' K Lime-stone CaCO 2 03 Bauxite of A1 0 1,000 Sulphur- 1 44 "phurous anhydride.

Emample 2.

In the preceding sulphide in a sufiicient proportion to give the required quantity of sulphur, taking into account the value of the radical S of this sulphide.'

In the case of coal-heated ovens, such as cupolas, water-jackets and the like, the reduction'of the metal present in the bauxite (-iron) and of the added sulphide forms a metallicm'at which, on account of its density, falls to the bottom of the oven-and separates from the oxy-silico-aluminate of calcium.

The following-is an example of the case 1 wherein a sulphide is added:

yrites containin 50 of sulphur {iron bi-sulphide @5 140 mixture, it is possible to by a natural or artificial mere heating. Such are ferrous or ferric sulphates, crude aluminum sulphate obtained by the action of sulphuric acid on bauxite, or crystallized aluminum sulphate or natural or artificial calcium sulphate. It-is known that iron sulphate and aluminum sulphate lose their acid radical and release S0 and O by mere heating, that calcium sulphate loses this radical by heating, in the presence of silica or carbon.

The particular case of crude or crystallized aluminum sulphate is interesting as it brings with its dissociation, a nascent homogeneous base A1 0 which has a great aflinity for combining with lime.

The following mixture gives an excellent result:

, Kgrms. Bauxite containing 60% of Al O 1,5 Lime-Bt'one 1,800 Crude aluminum sulphate -J 350 sulphates can be replaced by sulphites or hyposulphites which, under certain condi-' tlons, are capable of releasing S0 Whatever be the furnaces employed (cuolas, water-jackets, blast furnaces, electric urnaces, reverberatory furnaces the components can be introduced by successive charges, either roughly mixed, (min a previously crushed, mixed and briquetted state. In all cases, if the baking'has been well conducted, the clinker does not retain any appreciable trace of sulphur or of sulphurous or sulphuric acid. The clinker contains particles of metallic iron derived from the ox- .ides of iron in the bauxite, the said particles calcium and is no longer an inert or prejudicial body as is magnetic iron. 7

In accordance with current methods, the clinkers, after fine crushing are put on the market as aluminous cements.

I claim:

1. A process for the manufacture of aluminous cements from a mixture of bauxite and lime, comprising adding to the mixture compounds of sulphur capable of releasing sulphurous anhydride when the mixture is heated and in heating said mixture.

2. A process for the manufacture of aluminous cements comprising mixing bauxite, lime and a compound of sulphur and in heating the mixture.

3. A process for the manufacture of aluminous cements, comprising mixing bauxite, lime and aluminum sulphate and heating the mixture.

4. A process for the manufacture of aluminous cements, comprising mixing bauxite, lime, and compounds of sulphur capable of releasing sulphurous .anhydride and heating said mixture'in the presence of silica.

5. A process for the manufacture of aluminous cements, comprising mixing bauxite, lime and a sulphate which on dissociation produces a nascent base having great aflinity for I lime and in heating said mixture.

LoUrs GABRIEL PATROUILLEAU. 

